A variety of apparatus have been proposed to keep a driver of an automobile or similar alert and to prevent the driver from dozing off during driving. Such an apparatus usually includes a sensor for sensing that the driver has started to doze off and facilities for awakening the driver by receiving a signal from the sensor. For example, a sensor is known which senses that a driver has started to doze off by sensing the number of times the driver nods his head per unit of time or the number of times the driver leans his head forward or similar, because the driver nods his head when he starts to doze off, and so the sensor sends a signal to facilities for awakening the driver. Also, facilities are known for alerting a driver. The alerting facilities operate by receiving a signal and alerting the driver by producing a loud sound to the driver's ear(s). Therefore, according to the above described apparatus having a sensor and alerting facilities, if a driver starts to doze off, the sensor senses that the driver's head is leaning forward, and actuates the alerting facilities for alerting and awakening the driver.
However, because the above-mentioned apparatus operates only after a driver has started to doze off, the driver may lose his concentration, due to drowsiness, and cause a car accident when the driver has started to doze off to such a degree that the alerting facilities for alerting and awakening the driver may not be effective.
Accordingly, it is an object of the present invention to provide apparatus for effectively preventing a driver from dozing off by vibrating the seat in which the driver of the automobile is sitting.